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	<head>
		<title>three.js webgl - custom attributes [particles]</title>
		<meta charset="utf-8">
		<meta name="viewport" content="width=device-width, user-scalable=no, minimum-scale=1.0, maximum-scale=1.0">
		<link type="text/css" rel="stylesheet" href="main.css">
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	<body>
		<div id="info"><a href="https://threejs.org" target="_blank" rel="noopener">three.js</a> - custom attributes example - particles</div>
		<div id="container"></div>

		<script type="x-shader/x-vertex" id="vertexshader">

			attribute float size;
			attribute vec3 customColor;

			varying vec3 vColor;

			void main() {

				vColor = customColor;

				vec4 mvPosition = modelViewMatrix * vec4( position, 1.0 );

				gl_PointSize = size * ( 300.0 / -mvPosition.z );

				gl_Position = projectionMatrix * mvPosition;

			}

		</script>

		<script type="x-shader/x-fragment" id="fragmentshader">

			uniform vec3 color;
			uniform sampler2D pointTexture;

			varying vec3 vColor;

			void main() {

				gl_FragColor = vec4( color * vColor, 1.0 );
				gl_FragColor = gl_FragColor * texture2D( pointTexture, gl_PointCoord );

			}

		</script>

		<script type="importmap">
			{
				"imports": {
					"three": "../build/three.module.js",
					"three/addons/": "./jsm/"
				}
			}
		</script>

		<script type="module">

			import * as THREE from 'three';

			import Stats from 'three/addons/libs/stats.module.js';

			let renderer, scene, camera, stats;

			let sphere;

			const WIDTH = window.innerWidth;
			const HEIGHT = window.innerHeight;

			init();

			function init() {

				camera = new THREE.PerspectiveCamera( 40, WIDTH / HEIGHT, 1, 10000 );
				camera.position.z = 300;

				scene = new THREE.Scene();

				const amount = 100000;
				const radius = 200;

				const positions = new Float32Array( amount * 3 );
				const colors = new Float32Array( amount * 3 );
				const sizes = new Float32Array( amount );

				const vertex = new THREE.Vector3();
				const color = new THREE.Color( 0xffffff );

				for ( let i = 0; i < amount; i ++ ) {

					vertex.x = ( Math.random() * 2 - 1 ) * radius;
					vertex.y = ( Math.random() * 2 - 1 ) * radius;
					vertex.z = ( Math.random() * 2 - 1 ) * radius;
					vertex.toArray( positions, i * 3 );

					if ( vertex.x < 0 ) {

						color.setHSL( 0.5 + 0.1 * ( i / amount ), 0.7, 0.5 );

					} else {

						color.setHSL( 0.0 + 0.1 * ( i / amount ), 0.9, 0.5 );

					}

					color.toArray( colors, i * 3 );

					sizes[ i ] = 10;

				}

				const geometry = new THREE.BufferGeometry();
				geometry.setAttribute( 'position', new THREE.BufferAttribute( positions, 3 ) );
				geometry.setAttribute( 'customColor', new THREE.BufferAttribute( colors, 3 ) );
				geometry.setAttribute( 'size', new THREE.BufferAttribute( sizes, 1 ) );

				//

				const material = new THREE.ShaderMaterial( {

					uniforms: {
						color: { value: new THREE.Color( 0xffffff ) },
						pointTexture: { value: new THREE.TextureLoader().load( 'textures/sprites/spark1.png' ) }
					},
					vertexShader: document.getElementById( 'vertexshader' ).textContent,
					fragmentShader: document.getElementById( 'fragmentshader' ).textContent,

					blending: THREE.AdditiveBlending,
					depthTest: false,
					transparent: true

				} );

				//

				sphere = new THREE.Points( geometry, material );
				scene.add( sphere );

				//

				renderer = new THREE.WebGLRenderer();
				renderer.setPixelRatio( window.devicePixelRatio );
				renderer.setSize( WIDTH, HEIGHT );
				renderer.setAnimationLoop( animate );

				const container = document.getElementById( 'container' );
				container.appendChild( renderer.domElement );

				stats = new Stats();
				container.appendChild( stats.dom );

				//

				window.addEventListener( 'resize', onWindowResize );

			}

			function onWindowResize() {

				camera.aspect = window.innerWidth / window.innerHeight;
				camera.updateProjectionMatrix();

				renderer.setSize( window.innerWidth, window.innerHeight );

			}

			function animate() {

				render();
				stats.update();

			}

			function render() {

				const time = Date.now() * 0.005;

				sphere.rotation.z = 0.01 * time;

				const geometry = sphere.geometry;
				const attributes = geometry.attributes;

				for ( let i = 0; i < attributes.size.array.length; i ++ ) {

					attributes.size.array[ i ] = 14 + 13 * Math.sin( 0.1 * i + time );

				}

				attributes.size.needsUpdate = true;

				renderer.render( scene, camera );

			}

		</script>

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